HDFS脚本

环境准备

vim .bash_profile

export CLASSPATH=.:/home/hadoop/work/hadoop2.6jar/*.jar
source .bash_profile

1.上传文件到hdfs

vim CopyFile.java

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class CopyFile {
public static void main(String[] args) throws Exception {
        Configuration conf=new Configuration();
        FileSystem hdfs=FileSystem.get(conf);

        Path src =new Path("/home/hadoop/lijieran.txt");
        Path dst =new Path("hdfs://h201:9000/user/hadoop/");

        hdfs.copyFromLocalFile(src, dst);
                //hdfs.copyFromLocalFile(ture,ture,src, dst);
        System.out.println("Upload to"+conf.get("fs.default.name"));

        FileStatus files[]=hdfs.listStatus(dst);

        for(FileStatus file:files){
            System.out.println(file.getPath());
        }
    }
}

/usr/jdk1.7.0_25/bin/javac CopyFile.java

 /usr/jdk1.7.0_25/bin/java CopyFile

*****如果保错 :Wrong FS: hdfs://h101:9000/user/hadoop, expected: file:///***

把core-site.xml和hdfs-site.xml放到当前目录下

2、下载hdfs文件到本地

vim ToFile.java

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class ToFile {
public static void main(String[] args) throws Exception {
        Configuration conf=new Configuration();
        FileSystem hdfs=FileSystem.get(conf);

        Path src =new Path("hdfs://h201:9000/user/hadoop/lijieran.txt");
        Path dst =new Path("/home/hadoop/work");

        hdfs.copyToLocalFile(src, dst);

        System.out.println("Download to"+conf.get("fs.default.name"));

        FileStatus files[]=hdfs.listStatus(src);

        for(FileStatus file:files){
            System.out.println(file.getPath());
        }
    }
}

3、往hdfs下文件写数据

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class CreateFile {

    public static void main(String[] args) throws Exception {

        Configuration conf=new Configuration();
        FileSystem hdfs=FileSystem.get(conf);

        byte[] buff="hello hadoop world!
".getBytes();//byte字节类型，把字符串转化成字节类型
        Path dfs=new Path("hdfs://h101:9000/user/hadoop/hellow.txt");//目标端创建hellow.txt文件
        FSDataOutputStream outputStream=hdfs.create(dfs);//输出流创建
        outputStream.write(buff,0,buff.length);//在空文件中写入 写的（字节类型，int,int）从0开始到结束都写入

4、创建hdfs目录

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class CreateDir {
    public static void main(String[] args) throws Exception{

        Configuration conf=new Configuration();
        FileSystem hdfs=FileSystem.get(conf);

        Path dfs=new Path("hdfs://h101:9000/user/hadoop/TestDir");
        hdfs.mkdirs(dfs);
    }
}

创建文件touchs

5.重命名hdfs文件

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class Rename{
    public static void main(String[] args) throws Exception {

        Configuration conf=new Configuration();
        FileSystem hdfs=FileSystem.get(conf);

        Path frpaht=new Path("hdfs://h101:9000/user/hadoop/b1"); //旧的文件名
        Path topath=new Path("hdfs://h101:9000/user/hadoop/bb111");//新的文件名

        boolean isRename=hdfs.rename(frpaht, topath);//boolean型的括号里（源端，目标端）

        String result=isRename?"成功":"失败";

        System.out.println("文件重命名结果为："+result);

    }
}

6、删除hdfs文件

import org.apache.hadoop.conf.Configuration; 
import org.apache.hadoop.fs.FileSystem; 
import org.apache.hadoop.fs.Path; 

public class DeleteFile { 

    public static void main(String[] args) throws Exception { 

        Configuration conf=new Configuration(); 
        FileSystem hdfs=FileSystem.get(conf); 

        Path delef=new Path("hdfs://h101:9000/user/hadoop/bb111"); 
        
        boolean isDeleted=hdfs.delete(delef,false); 

        //递归删除  删除目录
        //boolean isDeleted=hdfs.delete(delef,true); 
        System.out.println("Delete?"+isDeleted); 
    } 
} 

7、查看文件是否为真

import org.apache.hadoop.conf.Configuration; 
import org.apache.hadoop.fs.FileSystem; 
import org.apache.hadoop.fs.Path;  

public class CheckFile { 
    public static void main(String[] args) throws Exception { 

        Configuration conf=new Configuration(); 

        FileSystem hdfs=FileSystem.get(conf); 

        Path findf=new Path("hdfs://h101:9000/user/hadoop/hellow.txt"); 

        boolean isExists=hdfs.exists(findf); 

        System.out.println("Exist?"+isExists); 

    } 
} 

8、 查看HDFS文件最好修改时间

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;


public class GetLTime {


    public static void main(String[] args) throws Exception {

        Configuration conf=new Configuration();
        FileSystem hdfs=FileSystem.get(conf);

        Path fpath =new Path("hdfs://h101:9000/user/hadoop/hellow.txt");

        FileStatus fileStatus=hdfs.getFileStatus(fpath);

        long modiTime=fileStatus.getModificationTime();

        System.out.println("file1.txt的修改时间是"+modiTime);
    }
}

****时间格式:Coordinated Universal Time(CUT) 协调世界时

9、查看hdfs文件

import java.io.InputStream;
import java.net.URL;

import org.apache.hadoop.fs.FsUrlStreamHandlerFactory;
import org.apache.hadoop.io.IOUtils;

public class URLcat{
        static {
                URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory());
        }

        public static void main(String[] args) throws Exception {
                InputStream in = null;
                try {
                        in = new URL(args[0]).openStream();//args[0]=hdfs://h201:9000/user/hadoop/lijieran.txt
                        IOUtils.copyBytes(in, System.out, 4096, false);
                } finally {
                        IOUtils.closeStream(in);
                }
        }
}

/usr/jdk/bin/java 文件 hdfs://h201:9000/user/hadoop/lijieran.txt